The invention relates to a method for producing a feeder configured for use in a casting mold used for casting metals, wherein the feeder has a feeder body enclosing a feeder cavity and a through opening in its base region for connecting the feeder cavity to the casting mold and the feeder body consists of an exothermic material and is enclosed on its outer side at least in regions by an external shell consisting of insulating refractory material, and wherein the feeder is provided with a feeder foot arranged externally in its base region and having an opening flush with the through opening.
EP 2 489 449 A describes a feeder, whose feeder body is made from an exothermic, heat-producing material, which upon contact with the hot metal, whose temperature increases in the feeder cavity during the founding process, is combustible. The feeder body is surrounded externally at least partially by an external shell made from an insulating, fire-proof material. In this manner, it should be possible that the external shell made from the insulating material stores the heat existing by the liquid metal and the exothermic reaction with the feeder body made from the exothermic material, so that an increase of the modulus of such a feeder relative to a feeder made exclusively from an exothermic material is provided. It is therefore unchanged that the feeder body made from the exothermic material, based on the exothermic reaction, in addition to the flowing liquid metal, releases a defined amount of heat, which must be so great that if necessary, existing heat loss of the entire feeder system is compensated, despite the additional insulating outer shell. Based on this effect, the module of a purely exothermal feeder with a feeder having an insulating external shell is increased, that is, with a constant module required on casting technical grounds, the dimensions of the feeder can be reduced, also taking into consideration the insulating shell.
Regarding formation of a defined breaking edge for the feeder residue existing after completion of the casting process and cooking of the metal on the casting part and between the feeder body and the casting mold, a feeder foot in the form of a disc-shaped breaker core or in the form of a funnel-shaped metal disc is arranged. With the feeder shown in EP 2 489 449, the external shell either reaches only to the feeder foot or surrounds it only on its outer side. Thus, with the known feeder, the disadvantage can occur that with subsequent application of the breaker core or the metal disc on the feeder body, no central application of the feeder foot occurs, which leads to problems during formation of the feeder in the casting mold; for example, the breaker core or the metal plate during placement of the feeder on the forming mandrel of the casting mold, based on a deficient accuracy of fit, falls off or tears. In this case, the corresponding casting mold is not useable.